Agile and adaptable lasers are currently in demand for a number of applications and uses. For example, numerous material processing applications such as milling, micro-fabrication, drilling, memory repair, etc. require pulsed laser systems which provide, among others, high pulse energy (50 μJ or higher), excellent pulse power stability, excellent beam quality (M2<1.1, astigmatism<10%, beam roundness>95%) and narrow linewidth (Δλ<0.5 nm). Moreover, great flexibility is often required in the control of the pulse temporal profile, such as pulse to pulse control over the temporal profile at low, medium and high (>100 kHz) repetition rates.
In some applications, in particular with respect to material processing using high power lasers, it can be advantageous to control or modify the spatial properties of the outputted light, such as the width of the beam or the spatial distribution of power therein. In addition, laser processing of materials often requires scanning the laser beam on a surface of a workpiece. It can thus be useful to actively control the spatial distribution of power.
When using pulsed light it may, in some cases, be useful to control the pulse-to-pulse beam overlap along the scanning axis. This pulse-to-pulse overlap (Op-p) is defined as:
            O              p        -        p              =          1      -                        V          scan                                      D            beam                    ×                      R            pulse                                ,where the beam diameter Dbeam corresponds to the dimension of the beam in the direction of the scanning axis, Vscan is the scanning speed and Rpulse is the pulse repetition rate.
This pulse-to-pulse overlap can be a critical parameter for the quality of the process results as well as for its efficiency. Furthermore, complex beam scanning and displacement systems can be burdensome for efficient processing.
In view of the above, there remains a need in the art for tools providing the efficient and active control of the spatial properties of high power laser beams, especially for material processing where the output beam spatial pattern can be controlled with non moving components at very high speed.